Table. Characteristics of Included Studies.
| Source | Study design, participants, No. | Female, % (age, mean [SD]) | BP definition | Data sourced or medication studied | Control group | Multivariate adjustment factors | Newcastle-Ottawa Scale scorea | |||
|---|---|---|---|---|---|---|---|---|---|---|
| Selection | Comparability | Exposure | Outcome | |||||||
| Bastuji-Garin et al,40 1996 (France) | Case-control, 332 | Cases: 50.0 (79.2 [10.1]); controls: 50.0 (77.0 [10.9]) | Clinical and immunopathologic features | Multicenter questionnaire | Patients with skin tumors matched for sex and age within 5 y at dermatology clinic | Number of medications, diuretics, and neuroleptics | 3 | 2 | 1 | NA |
| Bastuji-Garin et al,33 2011 (France) | Case-control, 546 | Cases: 64.3 (82.4 [8.7]); controls: 61.5 (82.2 [8.6]) | Clinical and immunopathologic features | Multicenter questionnaire | Patients with skin tumors or acute conditions matched for sex, age within 5 y, center, and place of residence | Age, sex, and place of residence | 3 | 2 | 1 | NA |
| Nozu and Mita,42 2010 (Japan) | Case-control, 36 | Cases: 80.0 (87.8 [3.2]); controls: 38.7 (83.3 [1.7]) | Clinical and immunopathologic features | Medical record review from a hospital | Disabled inpatients owing to cerebral stroke | NA | 1 | 0 | 2 | NA |
| Lloyd-Lavery et al,21 2013 (UK) | Case-control, 220 | Cases: 59.3 (81.5 [9.7]); controls: 49.3 (78.3 [8.5]) | Clinical and immunopathologic features | Medical record review from hospitals | Patients with skin tumors matched for sex and age within 5 y at dermatology clinic | Sex, age, cerebrovascular disease, and dementia as well as patient comorbidities for drugs that were significantly associated with BP in the univariate analysis | 3 | 2 | 2 | NA |
| Schaffer et al,44 2017 (Switzerland) | Case-control, 193 | Cases: 52.2 (77.6 [not reported]); controls: 33.5 (76.5 [not reported]) | Clinical and immunopathologic features | Hospital database | Patients with diabetes matched for age at endocrinology clinic | Sex, age, and calendar year | 2 | 1 | 2 | NA |
| Tan et al,45 2017 (Singapore) | Case-control, 420 | Cases: 50.0 (78.0 [11.2]); controls: (76.0 [12.6]) | Established criteria with corresponding histologic and immunologic investigations | Hospital record review | Matched for sex and age within 5 y at dermatology clinic | NA | 3 | 1 | 2 | NA |
| Benzaquen et al,41 2018 (France) | Case-control, 183 | Cases: 50.8 (78.7 [7.0]); controls: 50.8 (79.3 [7.0]) | Clinical and immunopathologic features | Medical record review from 3 hospitals | Patients matched for sex and age within 5 y at endocrinology clinic | Neurologic, metabolic or endocrine, and other dermatologic comorbidities | 3 | 2 | 2 | NA |
| Kridin and Bergman,22 2018 (Israel) | Case-control, 410 | Cases: 53.7 (79.1 [9.1]); controls: 53.7 (79.0 [9.0]) | Clinical and immunopathologic features | Hospital medical record review | Patients with diabetes and with hernia or skin lesion matched for sex, age, year of diagnosis, and ethnicity | Neurologic diseases and metformin intake | 4 | 2 | 2 | NA |
| Lee et al,15 2019 (Korea) | Case-control, 1340 | Cases: 49.0 (75.3 [10.0]); controls: 49.0 (75.3 [10.0]) | ICD-10 code L12.0 | National insurance database | Patients with diabetes matched for sex, age, and year of diagnosis | Neurologic, malignant, and psychological comorbid disorders and receipt of spironolactone and psycholeptics | 3 | 2 | 2 | NA |
| Rosenstock et al,50 2019 (27 countries) | Randomized clinical trial, 6979 | Treatment: 38.5 (66.1 [9.1]); controls: 35.7 (65.6 [9.1]) | According to clinical investigations and diagnosis in the centers | Linagliptin, 5 mg/d | Placebo once daily added to usual care | NA | NA | NA | NA | NA |
| Varpuluoma et al,46,47,48 2018, 2019 (Finland) | Case-control, 16 338 | Cases: 59.7 (76.6 [not reported]); controls: 60.0 (76.7 [not reported]) | ICD-9 codes 694.5A and 694.5B; ICD-10 code L12.0 | National insurance database | Patients with basal cell carcinoma matched for sex, age, and year of diagnosis within 2 y | Diabetes, Alzheimer disease, vascular dementia, other or unspecified dementia, Parkinson disease, multiple sclerosis, subarachnoid hemorrhage, intracerebral hemorrhage, cerebral infarction, and epilepsy | 2 | 2 | 2 | NA |
| Hung et al,49 2020 (Taiwan) | Cohort, 31 700 | Exposure: 48.2 (66.0 [11.9]); controls: 78.8 (66.0 [11.8]) | ICD-9-CM diagnosis code: 694.5 | National insurance database | Matched for sex, age, and index year | Age, sex, comorbidity (Charlson Comorbidity Index), season, location, urbanization level, and level of care | 3 | 2 | NA | 3 |
| Plaquevent et al,43 2019 (France) | Case-control, 227 187 | Cases: 46.3 (77.9 [9.3]); controls: NA | Clinical and immunopathologic features | Cases: medical record review from 21 departments; references: national insurance database | Indirect age standardization on the randomly sampled general population with stratification on sex and age | NA | 3 | 1 | 1 | NA |
Abbreviations: BP, bullous pemphigoid; ICD-9, International Classification of Diseases, Ninth Revision; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; ICD-10, International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; NA, not available.
a
Newcastle-Ottawa Scale (total points) with selection, comparability, and exposure or outcome domains, in which the total score ranges from 0 (lowest quality) to 9 points (highest quality).